The present disclosure relates to electronic circuits, systems and apparatuses, and in particular, to switching regulator circuits and methods.
Switching regulators are a very efficient approach for providing power supply voltage and current to electronic circuits and systems. Such regulators use one or more inductors and switches to store energy in magnetic fields generated as current flows through an inductor. Switches are used to selectively couple reference voltages to the inductor to either increase the energy in the inductor or allow the energy to flow to an output, for example. Accordingly, switching regulators are sometimes referred to as “switchers,” “converters” (e.g., a Boost Converter or Buck Switcher).
FIG. 1 shows an example Buck switching regulator. In a Buck switching regulator, the input voltage is typically greater than the output voltage. Boost switching regulators, on the other hand, have input voltages less than the output voltages. A variety of switching regulators exist that store energy in inductors and transfer the energy using switches. In this example, a constant (or direct current, “DC”) input voltage Vin is coupled to one terminal of a high side switch 103. The other terminal of the high side switch 103 is coupled to a terminal of an inductor (L) 101 and a terminal of a low side switch 102. Control circuit 104 turns switches on and off to produce a regulated output voltage Vout on capacitor Cout 199 into a load represented here as a load resistor Ro.
In some applications it is desirable to have a regulated voltage that can vary across a voltage range. For example, one application of switching regulators is in envelope tracking power amplifiers. In an envelope tracking application, a power supply voltage to a power amplifier is varied based on the input signal to be amplified so that the power amplifier receives a power supply voltage that optimizes the efficiency of the amplification process. Accordingly, a switching regulator may receive an envelope tracking signal to change the output voltage over time.
Typically, envelope tracking power supplies use a single Buck converter using slow high-voltage devices. The switching frequency is, therefore, limited and the switching regulator can only supply the low frequency content of the load current. The remainder of the load current is typically supplied from a high-speed linear amplifier. However, linear amplifiers are very inefficient and consume large amounts of power.
A wide variety of applications would benefit from a switching regulator architecture that has the ability to change output voltage quickly and efficiently.